1. Field of the Invention
The present invention relates to a lens barrel which includes a short focal length for a wide angle of view.
2. Description of the Related Art
Compact zoom cameras having a zoom lens whose focal length at the wide-angle extremity is approximately 28 mm, 35 mm or 38 mm have been popularized in recent years.
Such conventional compact zoom cameras have a problem where the illumination of the marginal area of an image is smaller than that of the center of the image due to the optical properties of the lens. Specifically, in compact cameras the vignetting factor tends to be small (approximately 50 percent, image height≈0.9Y) due to the lens design, thus resulting in a lack of light quantity of marginal rays even if the diaphragm is set to a small aperture.
To combat this problem, a compact zoom camera in which an iris diaphragm is incorporated in a shutter unit has been produced. However, such a shutter unit is complicated in structure and difficult to be controlled, which may cause deterioration in precision of the aperture size to thereby lose half the initial effect of adopting the diaphragm shutter.
To combat this problem, another type of compact zoom camera has been produced having a zoom lens to which modifications are made (e.g., redesigning the zoom lens a large-diameter zoom lens). However, such a modification inevitably increases the size of the compact zoom camera.